Faculty Profiles - SAITO, Nagahiro

Papers - SAITO, Nagahiro

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Accelerated Capacity and Cycling Performance via Facile Instantaneous Precipitation Induced Amorphization for Lithium-Ion Batteries Reviewed International coauthorship Open Access

Yang W., Huang J., Zhang Y., Saito N., Zhang Z., Yang L.

Small Methods Vol. 7 ( 11 ) 2023.11

Language：English Publishing type：Research paper (scientific journal) Publisher：Small Methods

Conversion-alloying anodes have garnered escalating attention with high theoretical capacity, however, they are seriously hindered by large volume distortion and capacity fading. To counter, structural modification needs more exploration. Herein, advantageous structure and high-performance are realized in new amorphous PbSb2O6 (PSO-a) nanosphere via facile instantaneous precipitation induced amorphization; conversion-alloying mechanism endows it with prominent lithium-storage capability; nanostructure can shorten ion-transfer distance and accommodate volume change outside the bulk of PSO-a; and loosely-stacked isotropic amorphous structure can enhance kinetics both at electrode/electrolyte interfaces and in the bulk. Volume change is synergistically stabilized from within to outside the bulk, leading to accelerated capacity and cycling. As expected, when employed in half-cells with 1 m LiPF6 in ethylene carbonate/diethyl carbonate/dimethyl carbonate/fluoroethylene carbonate (3:3:3:1 by mass) as electrolyte, glass microfiber filter as separator, and pure lithium foil as counter electrode, it realizes eminent performance with high specific capacity of 1512.6 mA h g−1 at 0.1 A g−1 and 755.1 mA h g−1 after 1000 cycles at 3 A g−1. To the best of the authors' knowledge, this is the first time PbSb2O6 is utilized as high-performance anode for lithium-ion batteries. Furthermore, this facile strategy provides a promising direction for high-performance amorphous anode material.

DOI： 10.1002/smtd.202300691

Correlation function of specific capacity and electrical conductivity on carbon materials by multivariate analysis Reviewed Open Access

Moon J., Yun H., Ukai J., Chokradjaroen C., Thiangtham S., Hashimoto T., Kim K., Sawada Y., Saito N.

Carbon Vol. 215 2023.11

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Carbon

An attention to a Li ion battery for electric vehicles has been attracted, but there are two huge problems: a short mileage and slow charging speed. Therefore, it is required to improve the specific capacity and electrical conductivity of the carbon material used for an anode and a conductive agent. To solve these problems, this study organized correlation analysis with descriptor vectors by collecting experimental properties including capacity and conductivity from 21 various types of carbon materials. Focusing on the flux of Li ion, it was found that the capacity was dependent on the intercalation of Li ions, which lead to propose the correlation equation based on the Hill equation. Furthermore, the intercalation occurred at the edge of basal plane lead an increase of the width of the gap between two graphene layers, followed by a diffusion through the basal plane, finally the expanded gap recovered its original width. Also, it was found that the variables which are sensitive to the conductivity are largely dependent on the defects and especially the number of graphene layers around the surface, which proposed a correlation equation that can predict the capacity and conductivity. To validate these functions, we checked the effectiveness of it with both experimental data from 27 previous studies and statistical method. As a result, it was confirmed enough to predict them. Finally, a candidate structure for improving the battery performance was proposed, thus our study aims to guide the exploration of electrode materials for LIBs.

DOI： 10.1016/j.carbon.2023.118479

Search for stable host materials as low-voltage anodes for lithium-ion batteries: A mini-review Reviewed International coauthorship

Zhang Y., Huang J., Saito N., Zhang Z., Yang L., Hirano S.i.

Energy Storage Materials Vol. 55 page： 364 - 387 2023.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Energy Storage Materials

The explosive demand for lithium-ion batteries (LIBs) in electric vehicles, portable electronics, and smart grids has spurred extensive research in recent years. The key to essential advances in LIBs depends on the search for stable host electrode materials with desirable energy and power densities. In the development of emerging stable host anode materials, the operating potential is an overlooked but crucial parameter because it deeply influences the energy, power, and safety of batteries. The ideal potential should not be too close to the lithium deposition potential like graphite (0.1 V vs. Li+/Li) which would trigger the formation of lithium dendrites under high rates, nor should be too high like spinel Li4Ti5O12 (> 1.5 V vs. Li+/Li) which compromises the batteries’ power and energy density. This mini-review firstly gives an account of several types of titanium-based and vanadium-based compounds as stable host anodes with the average operating potentials around or below 1 V vs. Li+/Li. The mechanisms for stable lithium storage and the origins of the low operating potentials are discussed by combining various characterization technologies. The key barriers and corresponding approaches are summarized for progressive electrochemical performance. Furthermore, several concise perspectives and challenges aiming at further theoretical prediction and practical application are provided.

DOI： 10.1016/j.ensm.2022.11.030

Nanoscale advanced carbons as an anode for lithium-ion battery Reviewed International coauthorship Open Access

Naraprawatphong R., Chokradjaroen C., Thiangtham S., Yang L., Saito N.

Materials Today Advances Vol. 16 2022.12

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Materials Today Advances

Nanoscale advanced carbons, including carbon nanotube, graphene, carbon nanosphere, porous carbon, and their derivatives, are represented as distinct types of material generate in various forms, structure dimensions, and properties. They feature a large specific surface area, excellent conductivity, high mechanical properties, tunable chemical functionality, and a broad potential window, which essentially require for lithium-ion battery systems. The nanoscale advanced carbons have been intensively researched and developed as a negative electrode component to improve battery performance. This review deliberately discusses structures, main properties, and synthesis methods that are directly related to the physical properties and chemical behaviors of the nanoscale advanced carbons. Moreover, currently good candidates for anode material for lithium-ion batteries were summarized. The importance of the primary function and the synergistic effect of nanoscale advanced carbons with active electrode species is emphasized. The systematic information from this review provides a promising tool that represents an essential reference for selecting anode electrode materials and designing the next generation of advanced lithium-ion batteries.

DOI： 10.1016/j.mtadv.2022.100290

Saccharide-originated fluorescent carbon dots synthesized by in-liquid plasma with controlled orderliness of carbon core through precursor alteration for selective and rapid metal ion detection Reviewed International coauthorship

Treepet S., Chokradjaroen C., Kim K., Saito N., Watthanaphanit A.

Materials Today Chemistry Vol. 26 2022.12

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Materials Today Chemistry

Carbon dots (CDs) have grown interested in replacing metal-based quantum dots due to their fluorescent properties with low toxicity. The green synthesis, therefore, represents a contribution to this research field. Here, we demonstrate the synthesis of CDs from simple saccharides, including fructose, glucose, and sucrose, using an eco-friendly method—solution plasma (SP)—by applying plasma in the aqueous solution of the precursor. Variations and characterizations are conducted to understand the role or influence of each synthesis parameter, i.e. saccharide precursor's molecular structure, solution pH (2, 5, and 8), and post-treatment method (freeze-drying and heat-drying), in the materials' structure and fluorescent properties. Blue light-emitting CDs are prepared from all precursors of pH 5 and 8 through SP, followed by heat-drying. Results show that SP is responsible for the carbon core formation, and thus the precursor type affects the carbon core's orderliness. Heat-drying causes oxidation on the CDs' surface, whereby OH functional groups change to C=O. Among all samples, the CDs synthesized from fructose at pH 5 (Fru-CDs-5) perform the best photoluminescence property, having the highest quantum yield (QY) of 9.16% and exhibiting an outstanding ability to detect Fe3+ ions. This is the first attempt to evince the potential use of SP to synthesize CDs from natural carbon sources and obtain CDs exhibiting superior fluorescence properties without any doping and complex synthesis steps. In addition to offering a new synthetic approach, this work specifies the role of the SP and the effect of the saccharide's molecular structure, which is the most relevant synthesis parameters mandatory to obtain tailored CDs with precise control.

DOI： 10.1016/j.mtchem.2022.101139

Graphitic N-doped graphene via solution plasma with a single dielectric barrier Reviewed Open Access

Niu J., Chokradjaroen C., Saito N.

Carbon Vol. 199 page： 347 - 356 2022.10

Language：English Publishing type：Research paper (scientific journal) Publisher：Carbon

Graphitic nitrogen-doped graphene (g-NG) with significantly high nitrogen content, i.e., 18.79 at.%, could be produced by the electrical discharge in liquid, so-called “solution plasma”, with a single dielectric barrier. The proposed system could reduce the excessive current, resulting in stabilizing the glow plasma and maintaining the overall temperature. It could promote the preservation of nitrogen atoms from evaporation during the synthesis process and the formation of a graphitic carbon framework. Moreover, the influence of the precursors, i.e., six-membered ring organic molecules with and without the substitution of nitrogen atoms and the nitrogen-based functional groups, was also investigated to provide the guideline for the synthesis of g-NG via this proposed method. The substitution of nitrogen atoms in the benzene ring could be used to synthesize g-NG with higher nitrogen dopants, compared to the benzene ring with only nitrogen-based functional groups.

DOI： 10.1016/j.carbon.2022.08.032

Cellulose nanofiber–MWCNT buckypaper engineered composite current collector/electrode for flexible and long-lasting semi-solid-state Li batteries Reviewed

Yonchai C., Spencer-Jolly D., Palasak P., Pakawanit P., Phatthanakun R., Kidkhunthod P., Saito N., Kasemchainan J.

Journal of Alloys and Compounds Vol. 1056 2026.2

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Alloys and Compounds

Flexible energy storage devices are attracting growing interest for use in next-generation electronics, including wearable sensors, flexible displays, and biomedical implants. However, their performance is often limited by the mechanical shortcomings of conventional composite electrodes that use metal-based current collectors, which lack the flexibility and durability required to withstand repeated deformation during battery operation. To address these challenges, new materials that combine high electrical conductivity with excellent mechanical resilience are emerging as promising alternative current collectors. This study investigates the effect of incorporating cellulose nanofiber (CNF) <a modified industrial byproduct> into multi-walled-carbon-nanotube (MWCNT) bucky-paper with varying CNF content (0, 1, 2, 5, and 10 wt%) to develop flexible and long-lasting electrodes for lithium-ion batteries using LiFePO<inf>4</inf> (LFP) as the cathode active material and the semi-solid-electrolyte of PEO-TEGDME-LiTFSI via facile and environmentally friendly processes. The electrodes’ microstructural, mechanical, electrical, and electrochemical properties were systematically evaluated using SEM, XRD, X-ray tomography, tensile testing, EIS, and galvanostatic cycling. The results show that 5-wt%-CNF in the bucky-paper optimally enhances the structural integrity, tensile strength (3.2 MPa), and strain (6.5 %) of the bucky paper without significantly compromising electrical conductivity (205 mS/cm). The electrochemical testing further reveals that the battery cells using 5-wt%-CNF-bucky-paper delivers a high discharge capacity (113.77 mAh/g at 1 C) lasting over 300 cycles with 97.58 % capacity retention. These findings demonstrate that CNF-enhanced MWCNT-bucky-paper offers durable and high-performance semi-solid-state Li-ion batteries with free-standing electrodes, paving the way for the development of flexible and lasting energy storage systems.

DOI： 10.1016/j.jallcom.2026.186594

Dual Structure-Directing Agents for Superstructure Formation in PtCoCu Ternary Alloy Electrocatalysts Reviewed

Wang P., Chae S., Yun H., Liu Y., Deng Z., Baek S., Pakkang N., Akceoglu G.A., Sawada Y., Saito N.

Journal of Physical Chemistry C Vol. 129 ( 51 ) page： 22390 - 22402 2025.12

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Physical Chemistry C

The development of high-performance Pt-based electrocatalysts with reduced metal loading is crucial for advancing proton exchange membrane fuel cell technology. Herein, we present a dual structure-directing agent approach for the precise formation of superstructures in uniform PtCoCu ternary alloy nanoparticles. Using zinc phthalocyanine for coordination-based composition control and dicyandiamide for carbon-mediated sintering suppression enabled molecular-level mixing and formation of an L1<inf>0</inf> face-centered cubic superstructure with exceptional uniformity and controlled electronic properties. The optimized L1<inf>0</inf>-Pt<inf>45</inf>Co<inf>24</inf>Cu<inf>31</inf> electrocatalyst exhibited remarkable oxygen reduction reaction activity with a mass activity of 2.13 A/mg<inf>Pt</inf> at 0.9 V vs the reversible hydrogen electrode, representing a 7-fold improvement over commercial Pt/C and exceeding the DOE 2025 target by 483%. The electrocatalyst also demonstrated excellent durability, retaining more than 70% of its initial mass activity after 30 000 potential cycles. Comprehensive density functional theory calculations revealed that ternary alloying optimized the Pt and overall d-band centers, which were located at −2.87 and −2.50 eV, respectively, clarifying the electronic origin of the enhanced electrocatalytic performance. This dual structure-directing strategy overcomes the conventional trade-off between ordered phase formation and particle size control, demonstrating the potential of a tailored precursor design for developing next-generation electrocatalysts with precisely controlled superstructures.

DOI： 10.1021/acs.jpcc.5c06519

Ceramic-topological polymer composite electrolytes: Interfacial engineering via dynamic coordination-driven networks for long-life, high-voltage solid-state lithium metal batteries Reviewed

Wei Z., Wu B., Yang Z., Hu A., Wang Y., Zhang Y., Huang J., Saito N., Chen L., Yang L.

Energy Storage Materials Vol. 83 2025.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Energy Storage Materials

Polymer-ceramic composite solid-state electrolytes offer transformative potential for high-energy-density lithium metal batteries but face challenges such as ceramic agglomeration and interfacial incompatibility. Herein, we report a ceramic-topological polymer composite electrolyte synthesized via in situ thermally initiated free radical polymerization. By the weak coordination-inducing effect between surface-modified Li<inf>1.3</inf>Al<inf>0.3</inf>Ti<inf>1.7</inf>(PO<inf>4</inf>)<inf>3</inf> (LATP@M) particles and a poly(ethylene carbonate) matrix, uniform ceramic dispersion and interfacial adhesion are achieved. Simultaneously, a topological polymer architecture establishes a "dynamic interfacial continuum", bridging ceramic domains and supporting efficient Li⁺ conduction. The resultant electrolyte exhibits a ceramic-rich "polymer-in-ceramic" structure, in which the LATP@M phase acts as the conducting network, suppressing dendrite growth while ensuring rapid ion transport. The optimized electrolyte demonstrates exceptional ionic conductivity (0.72 mS cm<sup>-1</sup>), a high Li⁺ transference number (0.75), and an ultra-wide electrochemical stability window (5.7 V vs. Li/Li⁺). Full cells paired with LiFePO<inf>4</inf> and LiCoO<inf>2</inf> cathodes deliver outstanding cycling stability and Coulombic efficiency (> 99.5 %), while flexible pouch cells retain functionality under mechanical abuse. This work provides a scalable strategy to harmonize ionic conduction, interfacial compatibility, and mechanical robustness in solid-state batteries, advancing the development of safe, long-lifespan energy storage systems.

DOI： 10.1016/j.ensm.2025.104686

Enhanced specific energy in fast-charging lithium-ion batteries negative electrodes via Ti-O covalency-mediated low potential Invited Reviewed Open Access

Huang J., Yang Q., Hu A., Liao Z., Zhang Z., Zheng Q., Ren Z., Zheng S., Zhang Y., Yang X., Xu Z., Zhang L., Zhu D., Wen W., Liu X., Orita A., Saito N., Wang L., Xia Y., Chen L., Lu J., Yang L.

Nature Communications Vol. 16 ( 1 ) 2025.12

Language：English Publishing type：Research paper (scientific journal) Publisher：Nature Communications

Developing lithium-ion batteries with high specific energy and fast-charging capability requires overcoming the potential-capacity trade-off in negative electrodes. Conventional fast-charging materials (e.g., Li<inf>4</inf>Ti<inf>5</inf>O<inf>12</inf>, TiNb<inf>2</inf>O<inf>7</inf>) operate at high potentials (>1.5 V vs. Li<sup>+</sup>/Li) to circumvent lithium plating, yet this compromises specific energy. A viable strategy for enhancing the specific energy is to reduce the potential while avoiding the lithium plating risk; however, the underlying mechanisms remain unclear. Here we demonstrate that enhancing Titanium-Oxygen covalency through pseudo-Jahn-Teller Effect distortion in Ruddlesden-Popper perovskites enables low-potential operation. The Li<inf>2</inf>La<inf>2</inf>Ti<inf>3</inf>O<inf>10</inf> negative electrode exhibits a working potential of 0.5 V vs. Li<sup>+</sup>/Li with initial 139.3 mAh g<sup>−1</sup> at 5 A g<sup>−1</sup> and 72.9% capacity retention after 5000 cycles. Full cells with LiNi<inf>0.8</inf>Co<inf>0.1</inf>Mn<inf>0.1</inf>O<inf>2</inf> positive electrodes deliver 3.45 V average discharge voltage-50% higher than conventional Li<inf>4</inf>Ti<inf>5</inf>O<inf>12</inf> | |LiNi<inf>0.8</inf>Co<inf>0.1</inf>Mn<inf>0.1</inf>O<inf>2</inf> systems-achieving 100 mAh g<sup>−1</sup> at 4 A g<sup>−1</sup>. Mechanistic analysis reveals low Li⁺ migration barriers and stable Ruddlesden-Popper perovskite frameworks enable rapid ion transport.

DOI： 10.1038/s41467-025-61461-2

Tuning electronic structure and ORR performance of PtPdCu catalysts via composition-controlled alloying Reviewed

Ukai J., Wang P., Akceoglu G.A., Chae S., Pakkang N., Sawada Y., Saito N.

Journal of Electroanalytical Chemistry Vol. 996 2025.11

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Electroanalytical Chemistry

Developing compositionally optimized low-Pt catalysts for the oxygen reduction reaction (ORR) remains a key challenge in advancing electrochemical energy conversion technologies. In this study, Pt-Pd-Cu ternary nanoalloys with varying compositions (Pt₅₁Pd₃₄Cu₁₅, Pt₄₀Pd₂₅Cu₃₅, and Pt₃₅Pd₂₃Cu₄₂) and a binary Pt₆₀Pd₄₀ alloy were synthesized via a modified polyol process under controlled conditions. The resulting nanoparticles exhibited improved morphological uniformity and alloy homogeneity. X-ray photoelectron spectroscopy (XPS) revealed composition-dependent electronic structure modulation, which influenced oxygen adsorption and desorption properties. Electrochemical characterization using cyclic voltammetry (CV), linear sweep voltammetry (LSV), and rotating disk electrode (RDE) measurements demonstrated that the Pt₄₀Pd₂₅Cu₃₅ alloy delivered the highest ORR mass activity (455 mA mg<sup>−1</sup> Pt + Pd), outperforming both the binary alloy and commercial Pt/C (197 mA mg<sup>−1</sup> Pt). The enhanced performance is attributed to the synergistic effects of controlled alloying, electronic redistribution, and increased electrochemical active surface area. While membrane electrode assembly (MEA) testing remains for future validation, these findings highlight the potential of Pt-Pd-Cu ternary alloys, particularly Pt₄₀Pd₂₅Cu₃₅, as promising ORR catalysts for next-generation fuel cells.

DOI： 10.1016/j.jelechem.2025.119370

Interlayer-intercalated tantalum disulfide enabling voltage reduction for enhanced sodium storage Reviewed International coauthorship

Yang W., Chen K., Wei Z., Huang J., Zheng Q., Zhang Y., Zhang L., Zhang Z., Saito N., Xia Y., Chen L., Yang L.

Chemical Engineering Journal Vol. 523 2025.11

Language：English Publishing type：Research paper (scientific journal) Publisher：Chemical Engineering Journal

The intercalation anode material demonstrates as a promising choice for SIBs due to favorable merits of stable structure and cycling, however, the relatively high working voltage impedes its employment. Herein, the design strategy of intercalating an alloying element of Pb into TaS<inf>2</inf> (PTS) is presented to lower the working voltage for SIBs anode. The working voltage of TaS<inf>2</inf> is effectively reduced upon the intercalation of Pb into nano interlayers, which also enlarges the interlayer spacing and elevates the specific capacity. The reversible mechanism and intact layered structure during discharge and charge promote volume change restraint of alloying element. Optimized reaction kinetics of active pseudocapacitive behavior, enhanced electron and ion transfer facilitates rate capability. Ultimately, PTS realizes reduced average working voltage by 0.6 V with long cycling of 17,000 cycles and considerable specific capacity of 229 mAh g<sup>−1</sup> after 17,000 cycles at 50C; PTS||NVP full-cell also achieves considerable specific capacity of 107.7 mAh g<sup>−1</sup> and high capacity retention ratio of 97 % after 130 cycles at 2C. The proposed structure not only contributes to reduced working voltage and enhanced specific capacity but also demonstrates a promising route of altering the working voltage of intercalation anode for SIBs.

DOI： 10.1016/j.cej.2025.167614

From spent zinc-carbon batteries to lithium-ion batteries: An eco-friendly method to recycle graphite Reviewed

Chinnakutti K.k., Yun H., Kheawhom S., Gao H., Tapia-Ruiz N., Kidkhunthod P., Nijpanich S., Sawada Y., Saito N., Kasemchainan J.

Journal of Energy Storage Vol. 134 2025.10

Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Energy Storage

The eco-friendly recycling of graphite from used zinc‑carbon (Zn[sbnd]C) batteries presents a viable and economical approach for the advancement of lithium-ion battery (LIB) anodes. This investigation involved the recovery of graphite through ball milling techniques, followed by a detailed structural characterization. XRD analysis showed that the ball milled graphite had a partially ordered structure with lattice parameters a = 2.4704 Å and c = 6.7516 Å, which is comparable to that of commercial graphite (a = 2.4725 Å and c = 6.7526 Å) and higher defect density (I<inf>D</inf>/I<inf>G</inf> = 1.069) as revealed by Raman spectroscopy as compared to commercial graphite (I<inf>D</inf>/I<inf>G</inf> = 0.22). TEM images showed increased structural disorder with broken layers and the XPS results further confirms the presence of predominant sp<sup>2</sup>-hybridized carbon with C–C/C=C peak at 284.70 eV. FTIR analysis revealed the presence of surface functional groups, such as C[sbnd]H bonds, indicating possible surface alterations in the recycling process. These structural characteristics, in particular higher defects, and disorder, promote Li-ion diffusion and surface reactivity. Ball milled graphite showed a specific capacity of 367.52 mAh/g at 1C, maintained over 200 cycles at a Coulombic efficiency of 99.05 %. This value is similar to that for commercial graphite with a capacity of 371.39 mAh/g and a Coulombic efficiency of ca. 100 %. Although the recycled graphite demonstrates a slightly reduced initial efficiency, it provides effective long-term stability, economic advantages, and positive environmental impacts. This work demonstrates that a safe and scalable approach to defect-engineered graphite with impressive electrochemical performance and provides promise of environmentally friendly anode for Li-ion battery applications.

DOI： 10.1016/j.est.2025.118244

Fabrication of Pt nanoparticles encapsulated by N, P co-doped carbon via solution plasma for the oxygen reduction reaction Reviewed

Ukai J., Wang P., Chae S., Akceoglu G.A., Pakkang N., Sawada Y., Saito N.

Journal of Electroanalytical Chemistry Vol. 994 2025.10

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Electroanalytical Chemistry

The oxygen reduction reaction (ORR) remains a performance-limiting step in fuel cells due to sluggish kinetics and the high cost of platinum-based catalysts. In this study, we report the synthesis of nitrogen and phosphorus co-doped carbon (NPC) encapsulating Pt nanoparticles via a solution plasma process, aiming to reduce Pt usage while enhancing catalyst activity and durability. Structural characterization confirmed a core–shell morphology, with Pt cores uniformly embedded in a conductive, heteroatom-doped carbon shell. X-ray photoelectron spectroscopy revealed active nitrogen species (pyridinic and graphitic N) and P-doping contributing to electron redistribution and active site formation. Electrochemical tests in alkaline media demonstrated that the resulting NPC@Pt catalyst exhibits superior ORR activity, with a four-electron transfer pathway, higher limiting current density, and significantly improved long-term stability compared to commercial Pt/C. These findings highlight the synergy of heteroatom doping and core–shell structuring in advancing cost-effective, durable ORR electrocatalysts for alkaline fuel cells.

DOI： 10.1016/j.jelechem.2025.119273

One nanometer matters: quantum-induced discontinuity in the oxygen reduction reaction catalyzed by platinum nanoparticles Reviewed

Deng Z., Liu Y., Wang P., Zhu Z., Pakkang N., Akceoglu G.A., Chae S., Sawada Y., Yang L., Saito N.

Journal of Materials Chemistry A Vol. 13 ( 37 ) page： 31065 - 31076 2025.9

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Materials Chemistry A

Quantum-induced discontinuity in the oxygen reduction reaction (ORR) catalyzed by Pt nanoparticles (NPs) occurs at the ∼1.0 nm scale. Using a controlled solution plasma method, we synthesized monodisperse, surfactant-free ∼1.0-nm Pt NPs uniformly supported on single-walled carbon nanotubes. Electrochemical evaluation revealed a pronounced deviation from the classical size-scaling behavior: the catalytic activity decreased with decreasing Pt NP diameter from 2.5 to 1.5 nm but unexpectedly increased at ∼1.0 nm. High-resolution structural and spectroscopic analyses confirmed a critical transition around 1.5 nm, which separates the classical metallic behavior from a regime governed by quantum confinement. Despite their partial structural disorder, these quantum-sized clusters exhibited superior ORR performance, attributed to discrete electronic states, altered d-band structures and a high density of low-coordination active sites. The catalysts also demonstrated high durability, retaining ∼90% of their reduction current after 2000 cycles with <5% particle growth in acidic media. In particular, the superior ORR performance at ∼1.0 nm is consistent with the formation of magic number clusters exhibiting high symmetry, closed shell stability, and facet-specific reactivity. These structures deviate from conventional crystal habits, favoring icosahedral or truncated geometries rich in undercoordinated edge and corner atoms. The resulting disruption of long-range order and emergence of localized quantum states redefine the catalytic paradigm at this scale. This abrupt improvement in ORR performance establishes a fundamental boundary between classical and quantum electrocatalysis. By reframing ultrasmall Pt NPs as quantum objects rather than miniature metals, this study introduces a new design principle: harnessing quantum effects and symmetry-driven structural motifs for the rational design of next-generation catalysts in sustainable energy technologies.

DOI： 10.1039/d5ta04934b

Voltage Regulation via Covalent Bond Strength to Increase Energy Density for Safe Fast-Charging Lithium-Ion Batteries Reviewed

Huang J., Yang Q., Yang W., Wei Z., Xu Z., Zhang L., Zhang Y., Zhang Z., Wang L., Zhu D., Wen W., Liu X., Orita A., Saito N., Xia Y., Chen L., Lu J., Yang L.

Advanced Functional Materials Vol. 35 ( 37 ) 2025.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Advanced Functional Materials

Safe fast-charging anodes with high operating voltage, such as Li<inf>4</inf>Ti<inf>5</inf>O<inf>12</inf> (≈1.55 V) and TiNb<inf>2</inf>O<inf>7</inf> (≈1.65 V), compromise the full-cell output voltage (2.3 V) to ensure safety, limiting the energy density. Lowering anode potential can effectively enhance energy density while maintaining safety; however, the mechanisms behind require further exploration. Here, methods are proposed to lower voltage by enhancing the M–L covalent bonding, achieved by reducing coordination number, electron-donating inductive effects, or utilizing pseudo-Jahn–Teller effect distortion. Using LiLaTiO<inf>4</inf> as a model anode, the pseudo-Jahn–Teller effect distortion of TiO<inf>6</inf> octahedra is explored to show how it adds covalency to Ti–O bonds, lowing the potential (≈0.3 V). Moreover, bulk LiLaTiO<inf>4</inf> exhibits excellent rate performance (181 mAh g<sup>−1</sup> at 1 A g<sup>−1</sup>, 122 mAh g<sup>−1</sup> at 10 A g<sup>−1</sup>) and good cycling stability (retention rate of 73% after 6000 cycles at 5 A g<sup>−1</sup>). NCM811//LiLaTiO<inf>4</inf> full cell demonstrates exceptionally high-power performance (118.4 mAh g<sup>−1</sup> at 10 C and 95.6 mAh g<sup>−1</sup> at 20 C), achieving a voltage of 3.6 V, 57% higher than the 2.3 V, enhancing energy density to levels of graphite-LiFePO<inf>4</inf> systems. These improvements are attributed to lithium storage sites with low hopping energy barriers and the structure stability of Ruddlesden–Popper perovskite, offering new insights for safe fast-charging anodes.

DOI： 10.1002/adfm.202422105

Achieving Waste-Valorized Anode Materials for Li-Ion Batteries by Surface Engineering of Recycled Graphite from Spent Zn–C Batteries Reviewed Open Access

Yun H., Chinnakutti K.K., Noerochim L., Nijpanich S., Pornprasertsuk R., Sawada Y., Saito N., Kasemchainan J.

ACS Sustainable Chemistry and Engineering Vol. 13 ( 34 ) page： 13908 - 13919 2025.9

Language：English Publishing type：Research paper (scientific journal) Publisher：ACS Sustainable Chemistry and Engineering

The conventional recycling of Zn–C batteries typically relies on either the disposal into landfills or the direct incineration, yielding adverse pollution and unnecessary carbon emissions to the environment and atmosphere. Even though one of the main components in the batteries, the carbon rod could serve as a valuable secondary carbon source. Herein, we present a sustainable method to recycle waste Zn–C battery graphite as high-performance lithium-ion battery (LiBs) anodes through thermal and alkaline (KOH) treatments. Extensive structural and surface analyses revealed that the optimized treatment (RG H–K) removed metal impurities and beneficial surface activation through defect generation and functional group stabilization. This facilitated lithium-ion transport kinetics along the activated surface architecture and stabilized solid–electrolyte interphase (SEI) formation. Electrochemical measurements showed excellent performance in which the specific capacity of RG H–K achieved 364.51 mAh/g at 0.2C and 255.88 mAh/g at 5C, along with stable long-term cycling (>200 cycles) at 1C, maintaining a capacity of ∼350 mAh/g. These findings highlight the potential of engineered surface modification in upcycling waste graphite into high-performance, environmentally sustainable LIB anodes.

DOI： 10.1021/acssuschemeng.5c04658

Breaking Strain-Capacity trade-off via Ferroelectrically coupled topological alloying in Bandgap-Modulated perovskite Reviewed

Yang W., Huang J., Zheng Q., Zhang Y., Zhang Z., Zhang L., Xu Z., Saito N., Xia Y., Chen L., Yang L.

Chemical Engineering Journal Vol. 515 2025.7

Language：English Publishing type：Research paper (scientific journal) Publisher：Chemical Engineering Journal

The development of stable anode constitutes a critical pathway for PIBs advancement, particularly in addressing the structural and capacity degradation induced by repetitive bulky K<sup>+</sup> (1.38 Å) storage. We present a crystallographic topology engineering strategy through Bi-doped lead titanate perovskite (BPT), achieving simultaneous capacity enhancement and ultra-stable cyclability via three synergistic mechanisms: (1) bandgap reduction coupled with grain refinement through Bi<sup>3+</sup> lattice substitution, enhancing intrinsic conductivity and reactions kinetics; (2) spontaneous polarization generating built-in electric fields lowering K<sup>+</sup> diffusion barriers; (3) topologically constrained alloying reactions within a rigid cubic framework enabling zero lattice strain during potassiation and depotassiation. The engineered BPT anode demonstrates breakthrough performance metrics: 76 % capacity retention through 7000 cycles at 500 mA g<sup>−1</sup> and considerable specific capacity (245 mAh g<sup>−1</sup> at 20 mA g<sup>−1</sup>). This work not only demonstrates zero-strain potassium storage but also introduces an approach for designing stress-immune alloying anodes through crystallographic topological engineering.

DOI： 10.1016/j.cej.2025.163654

Highly Dispersed PtPdCu Nanoparticles for Oxygen Reduction Catalytic Performance and Electronic State Reviewed

Wang P., Chae S., Deng Z., Liu Y., Zhu Z., Sawada Y., Saito N.

Journal of Physical Chemistry C Vol. 129 ( 20 ) page： 9302 - 9313 2025.5

Authorship：Last author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：Journal of Physical Chemistry C

In this study, we aimed to synthesize a ternary PtPdCu nanoalloy catalyst supported on commercially available carbon black. A one-step solvothermal method with the addition of urea was adopted to obtain alloy nanoparticles of uniform size. Results showed that the adsorption and desorption of oxygen intermediates were improved in Pt<inf>48</inf>Pd<inf>32</inf>Cu<inf>20</inf> nanoparticles, and the overpotential was greatly reduced. In addition, the RDE test demonstrated a mass activity of 917 mA mg-1 Pt + Pd, which is approximately five times higher than the mass activity of commercial Pt/C (197 mA mg-1 Pt). Furthermore, the accelerated stress test showed that PtPdCu exhibited superior stability compared with commercial Pt/C. In the H<inf>2</inf>-O<inf>2</inf> fuel cell, the maximum power output was 887 mW cm<sup>-2</sup>, with low Pt and Pd loading (13 wt % PtPd/C) on the cathode. X-ray photoelectron spectroscopy (XPS) analysis revealed that the introduction of Pd causes the center of the Pt valence band to shift to an appropriate position, thereby weakening the adsorption of oxygen-containing intermediates throughout the PtPdCu alloy and improving the catalytic performance.

DOI： 10.1021/acs.jpcc.5c01985

Synthesis of size-controlled PtPdIr nanoparticles by solution plasma sputtering and their catalytic properties Reviewed Open Access

Liu Y., Zhu Z., Deng Z., Wang P., Chae S., Sawada Y., Saito N.

Rsc Advances Vol. 15 ( 16 ) page： 12677 - 12688 2025.4

Language：English Publishing type：Research paper (scientific journal) Publisher：Rsc Advances

Platinum-based catalysts are widely used in polymer electrolyte fuel cells (PEMFCs) due to their excellent catalytic activity for the oxygen reduction reaction (ORR) and hydrogen oxidation reaction (HOR). In this study, a PtPdIr ternary alloy catalyst was synthesized by a solution plasma (SP) sputtering process with PtPd and PtIr erelctrodes, which provides a non-equilibrium reaction field in solution. The ratio of Ir in the PtPdIr nanoparticles increased as the ratio of Ir in the PtIr electrode increased. However, the ratio reamined constant at about 10%. The size of the nanoparticles could be controlled in the range of 1-3 nm. In addition, the nanoparticles were well dispersed when supported on carbon and no agglomeration was observed. The electrochemical properties of the obtained nanoparticles were investigated in terms of ORR and HOR, and the particle-c (79 : 14 : 7) nanoparticle exhibited the highest ORR and HOR performance. XPS analysis showed that the intensity of I<inf>Pd(ii)</inf> and I<inf>Pd(0)</inf> in particle-c (79 : 14 : 7) was at the same level, and that the chemical bonding state of these elements enhances ORR and HOR activity.

DOI： 10.1039/d5ra01747e

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